The present invention relates to devices for holding an air filter, and particularly a cylindrical air filter, in place.
A cylindrical air filter generally takes the form of a hollow cylinder open at both ends. In typical use, one end of the cylinder is sealed and filtering is accomplished by forcing air through the sides thereof by either forcing it in at the open end and hence out the sides, or drawing it out at the open end and hence in the sides.
To utilize the typical cylindrical air filter, a support structure or housing is usually provided to which, or in which, the filter is secured with one end thereof sealed. In the prior art, this has generally been accomplished by the use of a cone and yoke device. With this device, a cone with perforated sides is inserted into the first end of the air filter far enough that the sides of the cone press against the sides of the air filter at the first end. A threaded bolt is provided to extend from the tip of the cone past the second end of the filter. A metal sealing and clamping plate with a center hole is then placed over the second end of the filter, with the threaded bolt extending through the center hole. The entire arrangement is then secured in place with a wing nut tightened onto the end of the threaded bolt, whereby the plate is held pressed against the filter and the filter against the cone. Air may move into or out of the center of the filter only through its sides and the perforations in the cone. U.S. Pat. Nos. 4,171,963 (Schuler); 4,135,899 (Gauer); and 3,745,753 (Risse). While this cone and yoke arrangement is suitable for many uses, changing the filter requires access along the center axis. Accordingly, the cone and yolk arrangement is undesirable or unsuitable where axial access is limited or impossible.
U.S. Pat. No. 3,672,130 (Sullivan, et al.) uses spring clips and an annular recess in the sealing plate to support a cylindrical filter. French Pat. No. 1,569,381 uses a similar annular recess, but uses a layer of compressible plastic instead of spring clips. Like the cone and yoke system, these systems require axial access for filter replacement. Thus, they, too, are undesirable or unsuitable where axial access is limited or impossible.
It is the purpose of the present invention to provide a sealing and clamping apparatus which permits replacement of an air filter through an access on the side of the air filter support structure or housing, rather than along its axis. A significant reduction in the amount of clearance which must be allowed around the filter is thereby accomplished, making the present invention highly suitable for use in a duct line or other situations where side access and minimum space usage are desired.